As explained in the Adler application, an optical video playback device has many attractive attributes but it is subject to the practical limitation of maintaining proper conditions of focus which, of course, is necessary for optimum playback of video discs. The prior practices for achieving focus control, i.e., focus servo systems, aerodynamic stabilization of the disc, etc., are improved upon with the self-compensating focus system described in Adler's application. Adler's approach is attractive both because of the simplification it represents in comparison with prior techniques and because it lends itself more readily to production. The present invention constitutes an improvement in Adler's solution to the difficult problem of focus control in that it increases the useful operating range of a self-compensating system and further because it facilitates the implementation of self-compensating focus in practical forms for video playback devices.